Preparation of liquid crystal nanocapsules by polymerization of oil-in-water emulsion monomer droplets

Liquid crystal nanocapsules (LC-Nanocapsules) were prepared by miniemulsion polymerization of the oil-in-water emulsion monomer droplets dissolving the liquid crystal (LC) compounds. In order to establish the preparation conditions of LC-Nanocapsules exhibiting the liquid crystallinity, the effects of the capsule wall-forming monomers and the crosslinking agent concentration on the capsule structure were investigated in detail. The monodisperse colloidal products covered with the robust polymer shell wall was successfully prepared by the polymerization of the emulsion monomer droplets obtained through the phase inversion temperature emulsification technique using the amphiphilic block copolymer as an emulsifier. The endothermic peak was observed at the nematic-isotropic phase transition temperature (TNI) of the LC in the differential scanning calorimetry diagram of LC-Nanocapsules. The bright- and dark-field images of the dried thin films of LC-Nanocapsules spread on a glass substrate were found to appear repeatedly by the temperature change below and above TNI by polarized optical microscopic analysis. These results revealed that the LC-Nanocapsules with a complete engulfing morphology were successfully formed by the spontaneous coacervation phenomena between the crosslinked polymer and the LC with a progression of the polymerization, as theoretically predicted from the viewpoint of the spreading coefficients.